Influence of sulfur fertilization on S-containing, phenolic, and carbohydrate metabolites in rosy garlic (Allium roseum L.): a wild edible species in North Africa

Natural Antioxidants, Health Effects and Bioactive Properties of Wild Allium Species

BACKGROUND

There is an increasing interest from the pharmaceutical and food industry in natural antioxidant and bioactive compounds derived from plants as substitutes for synthetic compounds. The genus Allium is one of the largest genera, with more than 900 species, including important cultivated and wild species, having beneficial health effects.

OBJECTIVE

The present review aims to unravel the chemical composition of wild Allium species and their healthrelated effects, focusing on the main antioxidant compounds. For this purpose, a thorough study of the literature was carried out to compile reports related to health effects and the principal bioactive compounds. Considering the vast number of species, this review is divided into subsections where the most studied species are presented, namely Allium ampeloprasum, A. flavum, A. hookeri, A. jesdianum, A. neapolitanum, A. roseum, A. stipitatum, A. tricoccum, and A. ursinum, with an additional composite section for less studied species.

METHODS

The information presented in this review was obtained from worldwide accepted databases such as Scopus, ScienceDirect, PubMed, Google Scholar and Researchgate, using as keywords the respective names of the studied species (both common and Latin names) and the additional terms of"antioxidants" "health effects" and "bioactive properties".

CONCLUSION

The genus Allium includes several wild species, many of which are commonly used in traditional and folklore medicine while others are lesser known or are of regional interest. These species can be used as sources of natural bioactive compounds with remarkable health benefits. Several studies have reported these effects and confirmed the mechanisms of action in several cases, although more research is needed in this field. Moreover, considering that most of the studies refer to the results obtained from species collected in the wild under uncontrolled conditions, further research is needed to elucidate the effects of growing conditions on bioactive compounds and to promote the exploitation of this invaluable genetic material.

Nutritional Value, Chemical Characterization and Bulb Morphology of Greek Garlic Landraces

Garlic (Allium sativum L.) is an important vegetable crop throughout the world. In Greece there are many areas which have specialized in garlic cultivation through the last decades, considered the main production areas. However, despite the significance of garlic as a food product and the high annual income of this crop, there is a decreasing trend in total cultivated area in Greece, and the local landraces are gradually neglected in favor of new imported genotypes. In the present study, garlic genotypes (local landraces/varieties, imported genotypes, commercial cultivars) from the main production regions of Greece were assessed for their chemical composition and quality (total soluble solids, dry matter content, nutritional value, mineral composition, organic acids, fatty acids content and free sugars content), and bulb morphology. The results of the present study showed significant diversity in quality features and bulb morphology, not only between the genotypes from different growing regions, but also between those of the same region. This result is interesting since it could be implemented for further improvement and valorization of this important vegetable crop through extensive breeding programs within the framework of sustainability and genetic, material conservation.

Selenium and Sulfur to Produce Allium Functional Crops

Selenium is an element that must be considered in the nutrition of certain crops since its use allows the obtaining of biofortified crops with a positive impact on human health. The objective of this review is to present the information on the use of Se and S in the cultivation of plants of the genus Allium. The main proposal is to use Allium as specialist plants for biofortification with Se and S, considering the natural ability to accumulate both elements in different phytochemicals, which promotes the functional value of Allium. In spite of this, in the agricultural production of these species, the addition of sulfur is not realized to obtain functional foods and plants more resistant; it is only sought to cover the necessary requirements for growth. On the other hand, selenium does not appear in the agronomic management plans of most of the producers. Including S and Se fertilization as part of agronomic management can substantially improve Allium crop production. Allium species may be suitable to carry out biofortification with Se; this practice can be combined with the intensive use of S to obtain crops with higher production and sensory, nutritional, and functional quality.

Chemical composition and bioactive compounds of garlic (Allium sativum L.) as affected by pre- and post-harvest conditions: A review

Garlic (Allium sativum L.) is considered one of the twenty most important vegetables, with various uses throughout the world, either as a raw vegetable for culinary purposes, or as an ingredient of traditional and modern medicine. Furthermore, it has also been proposed as one of the richest sources of total phenolic compounds, among the usually consumed vegetables, and has been highly ranked regarding its contribution of phenolic compounds to human diet. This review aims to examine all the aspects related with garlic chemical composition and quality, focusing on its bioactive properties. A particular emphasis is given on the organosulfur compounds content, since they highly contribute to the effective bioactive properties of garlic, including its derived products. The important effects of pre-harvest (genotype and various cultivation practices) and post-harvest conditions (storage conditions and processing treatments) on chemical composition and, consequently, bioactive potency of garlic are also discussed.

The role of sulphur on the content of total polyphenols and antioxidant activity in onion (Allium cepa L.)

Sulphur is one of the most important elements in plants. Sulphur also positive influences on growth functions (nitrogen metabolism, enzyme activity and protein and oil synthesis), yield and quality bulbs of onion. In this experiment was watched the progress of making the total polyphenols content in different levels of fertilizer sulphur in onion during vegetation. In the work we watched also the influence of sulphur fertilization on the antioxidant activity. Sulphur was added in amounts 7.3 mg.kg-1 S, 11 mg.kg-1 S and 14,6 mg.kg-1 S. Samples of fresh onion we collected at the beginning, in the middle and in the end of vegetation period and we prepared an extract: 50 g cut onion extracted by 100 ml 80% ethanol according sixteen hours. These extracts were used for experiment. The content of total polyphenols was estimated by using Folin-Ciocalteau reagent. The absorbance was measured at 765 nm of wave length against blank. Antioxidant activity was measured using a compound DPPH˙ (2.2-diphenyl-1-picrylhydrazyl) at 515.6 nm in the spectrophotometer. Our values of total polyphenolic content during vegetation period  were in range from 508.16 ±27.59 mg.kg-1 to 638.2 ±12.84 mg.kg-1. The highest content of total polyphenolics was recorded at the end of the vegetation period (638.32 ±12.84 mg.kg-1) in III. sampling (incorporation of sulphur in quantity of 14.6 mg S.kg-1soil). This increase was statistically significant (P-value = 2.10-3). The lowest content of total polyphenols was measured in  the middle of vegetation period  (415.41 ±13.32 mg.kg-1) in II. sampling (incorporation of sulphur in quantity of 11 mg S.kg-1soil). Another indicator that has been evaluated and compared was the influence of sulphur fertilization on the antioxidant activity. The highest values of antioxidant activity were recorded at the end of vegetation period in all variants. The lowest value of antioxidant activity (25.41 ±7.67%) was measured in three sampling in II.variant.